In the past, rubbery, elastomeric-type polymers have been prepared by the reaction of an isocyanate with a diol or triol compound in the presence typically of a tin catalyst and an amine-type (Dabco) catalyst combination. The elastomeric polymer so produced generally contains mostly urethane linkages and is not fully cross-linked, and as such it tends to melt at relatively low temperatures; for example, under 180.degree. F. The cure time of the polymer often extends to 20 or 30 minutes, and, while the ingredients may be premixed and reacted for some applications, they clearly are not suitable for use in sprayable-type applications, wherein the ingredients are sprayed onto a surface substrate as a coating or sprayed into foam form.
Reaction-injection molding (RIM) techniques have been employed to prepare cured urethane compositions and typically comprise reacting components of a polyisocyanate with another component of a polyol within a nozzle and into an open-mold cavity. However, such RIM urethane compositions are not suitable for use in spraying operations, wherein the components of the composition are sprayed through a narrow orifice, and the spray compositions tend to pick up air and to lead to polymer breakdown, due to shearing forces in the spray nozzle. Further, sprayable compositions must be compounded, to provide for a stoichiometric reaction of the ingredients and to cure very rapidly, so that the spray compositions may be sprayed on horizontal and vertical surfaces, such as ceilings and walls, and quickly react, gel and cure.